<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div id="app">
    <div v-if="count == 3">div1</div>
    <div v-else-if="count == 4">div2</div>
    <div v-else>div3</div>
    <hr>
    <div v-show="count == 3">div v-show</div>

    <br>

    <input v-model="count">
</div>

<script src="js/vue.js"></script>
<script>

  //1.创建vue的核心对象
  new Vue({
    el:"#app",
    data(){
      return {
        username:"",
        url:"https://www.baidu.com",
        count:3
      }
    },
    methods:{
        show(){
            alert("我被点了")
        }
    }
  });


</script>

</body>
</html>